Novel and innovative sustainable HNFM@FeCl4 DES as an electrolyte, solvent, and catalyst for rapid electro-organic synthesis of spirooxindole and 4H-pyran derivatives with cytotoxicity assessment

The use of solvents, catalysts, and electrolytes in industrial processes presents significant environmental challenges, particularly in wastewater management. This study introduces a novel and sustainable deep eutectic solvent (DES) composed of HNFM and FeCl₄, designed as a reusable electrolyte, solvent, and catalyst aimed to rapid electro-organic synthesis of spirooxindole compounds 5(a–f) and 4H-pyran derivatives 6(a–h) with yields ranging from 90 to 97%. The synthesis is conducted at room temperature under a 5 mA current using graphite rods as low-cost and readily available anodes and cathodes, completing the process in just 20 min. The innovative 4-formylmorpholin-4-ium iron (III) chloride (HNFM@FeCl₄) DES not only enhances the efficiency of electrochemical reactions but also addresses environmental concerns associated with conventional solvents, catalysts, and electrolytes. By utilizing low-cost electrodes, this DES is both biodegradable and nontoxic, making it a sustainable alternative in electro-organic synthesis. This synthesis method demonstrates significant progresses in the reaction procedure and yields, showcasing the potential of this DES in organic synthesis applications. This research highlights the dual advantage of utilizing a green electrolyte while producing biologically relevant compounds, paving the way for more sustainable practices in electro-organic synthesis. The synthesized derivatives were identified through melting point analysis, FT-IR, 1HNMR, and CHN analysis. Additionally, an in vitro cytotoxicity assessment of the synthesized compounds reveals promising results, indicating their potential therapeutic benefits. The synthesized spirooxindole 5(a–f) and 4H-pyran 6(a–h) derivatives were then assessed for in vitro cytotoxic effects on the human colorectal adenocarcinoma cell line (HT-29) and human breast cancer cell line (MCF-7). All compounds demonstrated IC₅₀ values lower than 10 µM for the MCF-7 and HT-29 cell lines, indicating strong potential in anticancer activity. Remarkably, derivatives 5(a–f) demonstrated fantastic efficacy in inhibiting the viability of the HT-29 and MCF-7 cell line in comparison with commercial anticancer agent Doxorubicin which utilized as a positive control in this research.

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